The present invention relates to a curable resin composition, particularly an adhesive composition, having a quick curing property. More particularly, it relates to an adhesive composition suitable for assembling a field system of a speaker.
There has been an increasing use, year after year, of a cold quick-curing adhesive which is curable at a normal or room temperature in a short period of time, with a view to labor-saving, resource-saving and energy-saving.
Especially in assembling a speaker, various materials such as metal, magnetic material, paper and cloth are bonded, and it is required to carry out assembling the speaker made of such various materials in a short period of time. Accordingly, an adhesive composition is desired which is capable of bonding such materials in a short period of time.
Usually, a speaker has a construction as shown in FIG. 1. Namely, a frame 4 is bonded to a field system comprising a bottom plate 1, a ring-shaped magnet 2 and a ring-shaped top plate 3 which are laminated and bonded. To the peripheral portion of this frame 4, the peripheral portion (the cone edge) 7 of a cone 6 is bonded. To the center portion of this cone 6, a voice coil 8 is bonded. The intermediate portion of this voice coil 8 is held by a damper 9, and the lower portion of the voice coil 8 is fitted on the center portion of the bottom plate 1. A dust cap 10 is bonded to the center upper surface of the cone 6. As shown in FIG. 2, the voice coil 8 has a paper tape 11 wound on its outer circumference, and a coil 12 is wound on the outer circumference of the paper tape 11.
Particularly, bonding of the field system of a speaker comprising a bottom plate 1, a magnet 2 and a top plate 3 is as shown in FIG. 2. Namely, the field system of a speaker is assembled by bonding and laminating the bottom plate 1, the magnet 2 and the top plate 3 sequentially by an adhesive composition 13.
Heretofore, as a cold quick-curing adhesive, a two-pack type quick-curable epoxy adhesive, an anaerobic adhesive, an instantaneous adhesive or a second generation acrylic adhesive (SGA) has been known.
The two-pack type quick-curing epoxy adhesive is designed so that a main agent and a curing agent are weighed, mixed and coated on an adherent, whereupon the adhesive cures by the reaction of the main agent and the curing agent. However, such a two-pack type quick-curing epoxy adhesive has had a drawback that if weighing or mixing of the main agent and the curing agent is inadequate, the bond strength is likely to be remarkably low, and even if weighing and mixing are adequately carried out, the peel strength and impact strength tend to be low.
The anaerobic adhesive is designed so that the adhesive composition is pressed between adherends to cut off air for curing. However, it has had a drawback that if a part of the adhesive composition is squeezed out at the time of pressing, such a squeeze-out portion will be in contact with air and will not be cured. Further, it has another drawback that it is not curable when a clearance between adherends is large.
The instantaneous adhesive usually comprises cyanoacrylate as the main component and is excellent in the operation efficiency. However, it has had a drawback that the peel strength or impact strength is low. Further, the moisture resistance or water resistance is poor, whereby the range of its application is limited.
SGA is a two-pack type. Nevertheless, it requires no accurate weighing of the two liquids, and it cures at room temperature in a few or a few tens minutes even when weighing or mixing is inadequate, in some cases, simply by contacting the two liquids without requiring accurate weighing of the two liquids. Accordingly, it is excellent in the operation efficiency and yet SGA provides high peel strength or impact strength, and curing of the squeeze-out portion is also good. For this reason, it is widely employed (JP-B-58-34513, JP-B-58-5954 and JP-A-54-141826).
However, SGA usually takes a long time for curing, and it is difficult to accelerate the curing. In order to accelerate the curing of SGA, an attempt has been made to increase the amount of an organic peroxide, a reducing agent or a (meth)acrylic acid (JP-B-53-24103). However, if the amount of an organic peroxide is increased in order to accelerate the curing, there has been a problem that the storage stability tends to be poor. If the amount of the reducing agent is increased, there has been a problem that an unreacted reducing agent remains in the cured product, whereby the bond strength tends to be low. If the amount of the (meth)acrylic acid is increased, the curing can be accelerated, but unreacted (meth)acrylic acid tends to remain in the cured product, thus leading to a problem of causing rust to a metal, or corroding and breaking e.g. a copper wire.
In recent years, as a speaker, there has been an increasing demand for a speaker to be mounted on a vehicle, to be used for automobiles. The temperature in an automobile changes vigorously, for example, from a low temperature of xe2x88x9240xc2x0 C. to a high temperature of 85xc2x0 C., depending upon the weather of the particular region, the seasonal change from winter to summer, and the operation or termination of the engine. Accordingly, high thermal shock resistance has been required for a speaker to be mounted on a vehicle, particularly for a field system of a speaker to be mounted on a vehicle. Here, the thermal shock resistance is a bond strength against a vigorous temperature change i.e. in an environment of rapid heating or rapid cooling. If the thermal shock resistance is poor, there will be a problem that the bottom plate 1, the magnet 2 and the top plate 3 tend to peel, or the magnet 2 tends to break, whereby the speaker will not function properly.
The present inventors have conducted an extensive study and as a result, have found that the above problems can be solved by using compounds having specific structures. The present invention has been accomplished on the basis of this discovery.
Namely, the present invention provides:
A curable resin composition comprising:
(1) a compound having a structure of the formula (A) and/or (B):
R2xe2x80x94OOCxe2x80x94R1xe2x80x94COOxe2x80x94R2xe2x80x2xe2x80x83xe2x80x83(A)
xe2x80x83wherein R1 is xe2x80x94(CH2)nxe2x80x94 (wherein n is from 4 to 6), or an o-, m- or p-phenylene group, and each of R2 and R2xe2x80x2 is a C1-10 alkyl group, 
xe2x80x83wherein R3 is a C1-4 alkyl group,
(2) a polymerizable vinyl monomer,
(3) an organic peroxide,
(4) a reducing agent, and
(5) an elastomer component.
The curable resin composition which contains (6) an acid phosphate compound of the formula (C): 
wherein R is CH2=CR4CO(OR5)mxe2x80x94 (wherein R4 is hydrogen or a methyl group, R5 is xe2x80x94C2H4xe2x80x94, xe2x80x94C3H6xe2x80x94, xe2x80x94CH2CH(CH3)xe2x80x94, xe2x80x94C4H8xe2x80x94, xe2x80x94C6H12xe2x80x94 or 
and m is an integer of from 1 to 10), and n is an integer of 1 or 2.
The curable resin composition wherein (1) the compound having a structure of the formula (A) is di-2-ethylhexyl adipate and/or di-n-octyl phthalate.
The curable resin composition wherein (1) the compound having a structure of the formula (B) is methylacetyl ricinolate and/or butylacetyl ricinolate.
The curable resin composition wherein (2) the polymerizable vinyl monomer is an acrylate and/or a methacrylate.
The curable resin composition wherein (2) the polymerizable vinyl monomer is at least one member selected from the group consisting of 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, methyl acrylate and methyl methacrylate.
The curable resin composition wherein (5) the elastomer component is at least one member selected from the group consisting of an acrylonitrile-butadiene-methacrylic acid copolymer, an acrylonitrile-butadiene-methyl methacrylate copolymer, a butadiene-styrene-methyl methacrylate copolymer and an acrylonitrile-butadiene rubber.
The curable resin composition wherein (5) the elastomer component is an acrylonitrile-butadiene-methacrylic acid copolymer.
The curable resin composition which is a two-pack type curable resin composition comprising a first pack and a second pack, wherein the first pack contains at least the organic peroxide, and the second pack contains at least the reducing agent.
An adhesive composition containing the curable resin composition.
A cured product of the adhesive composition.
A composite comprising adherends bonded by the cured product.
The composite wherein the adherends are made of ceramics and/or metal.
The composite wherein the adherends are made of ceramics and metal.
The composite wherein the ceramics is a magnet.
The composite wherein the adherends are a frame and a cone of a speaker, which are bonded to each other along their peripheral portions, and/or a bottom plate, a magnet and a top plate of a speaker, which are laminated and bonded to form a field system of the speaker.
The composite wherein the adherends are a bottom plate, a magnet and a top plate of a speaker, which are laminated and bonded to form a field system of the speaker.